Crossbar tandem office for telephone systems



J. B. Nx-:wsoM 2,559,312

6 Sheets-Sheet l July 3, 1951 CROSSBAR TANDEM OFFICE FOR TELEPHONE SYSTEMS Filed Noy. 17, 1948 July 3, 1951 4 J. B. NEwlsoM I CROSSBAR TANDEM OFFICE FOR TELEPHONE SYSTEMS Filed Nov. 17, 1948 6 Sheets-Sheet 2 QON III-

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6 Sheets-Sheet 3 J. B. NEWSOM CROSSBAR TANDEM OFFICE FOR TELEPHONE SYSTEMS July 3, 1951 Filed Nov. 17, 194s AZ'TORNE Y /NVENTOR By J.B.NEW$0M J. B. Nl-:wsoM

CROSSBAR TANDEM OFFICE FOR TELEPHONE SYSTEMS July 3, 1951 .I Dus.

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Filed Nov. 17, 1948 A TTO/QNEV AJuly 3, 1951 J. B. NEwsoM CROSSBAR TANDEM OFFICE FOR TELEPHONE SYSTEMS Filed NOV. 17, 1948 6 Sheets-Sheet 5 J. B. NEwsoM cRossAR TANDEM OFFICE FOR TELEPHONE SYSTEMS Filed Nov. 17, 1 948 July 3," 1951 6 Sheets-Sheet 6 INI/ENTOR By J. B. NEWSOM Wfl? ATTORNEY Patented July 3, 1951 CROSSBAR TANDEM OFFICE FOR TELEPHONE SYSTEMS James B. Newsom, Great Neck, N. Y., assigner to Bell Telephone Laboratories, Incorporated, New `Herk, N. Y., a corporation of New York Application November 17, 1948, Serial No. 60,503

11 Claims. l.

This invention relates to telephone systems, and more particularly, to equipment in a tandem oliee.

On telephone connections through a cross bar tandem oce, a marker in the tandem oflice controls the establishment of the connection between the tandem trunk and the trunk to the required terminating oice or operators position. The marker receives from the tandem sender the designation of the terminating oflce or position in the form of a code. This code may be trans mitted from the originating oflice to the tandem sender by means of revertive pulses, dial pulses, or multifrequency pulses. It is the translation function of the marker to convert this code, comprising a combination oi two or more code digits, into a circuit path whereby a single route relay, corresponding to this code, may be operated. This route relay may then be suitably wired, by means of cross-connections for example, to direct the marker in the establishment of the connection between the tandem trunk and the ter-A minating oce or position.

The marker in a tandem oce must be capable of translating not only twoand three-digit oilice codes, but also may be required to control the establishing of connections to a variety of service positions which are designated by special types of codes.

An object of this invention is to provide a tandem marker capable of receiving from a tandem sender and translating both two-digit and three-digit office codes.

Another object of this invention is to provide a tandem marker capable of receiving from a tandem sender and translating a special type of code known as a service code.

Another object of this invention is to provide a tandem marker capable of receiving from a tandem sender and translating a special service code known as a TX code, functioning to perform that translation whether the TX code be a twodigit or a three-digit code.

In general, these objects have been attained by providing a plurality of groups of relays each serving to perform a translating function whereby the digits registered in the sender are progressively combined until a single route relay, corresponding to those combined digits, is operm ated to control the establishing of the connection from the tandem trunk to the desired o'rlice, ser vice position,` or special service position. A pair of relays is also provided one of which is operable when a special service code is registered in the sender, and the other of which is operable under y all other conditions, whereby diierent combinations of groups of relays are used to perform the translations.

These and other features of the invention will be more clearly understood from a consideration of the following description in connection with the accompanying drawings in which:

Fig. l shows, in diagrammatic form, equipment at an originating oiice as well as an incoming trunk at a tandem oiice, to illustrate a connection established by revertive pulsing between the originating olice and a revertive pulse tandem sender;

Fig. 2 shows, in diagrammatic form, a sender link and controller circuit, a revertive pulse sender, and marker connectors, detailed circuits being shown only for those features involved in the code translation;

Fig. 3 shows, in diagrammatic form, the code translation features of the marker;

Fig. 4 shows, in diagrammatic form, equipment at an originating olce, a tandem trunk circuit, and a sender link circuit, to illustrate a connection established by multifrequency pulsing between the originating oice and a multifrequency tandem sender.

Figs. 5, 6 and '7 show a multifrequency pulse receiving circuit and the multifrequency sender relays concerned in the registering of the olice 3m code and Fig. 8 shows the manner of arranging Figs. l to '7 inclusive.

Where reference is made in the following description to relays or leads with functional designations, the numeral shown in parenthesis following the functional designation is the ligure number.

No details of the originating and terminating office or of much of the equipment immediately 403., associated with the tandem` senders and marker tion of W. T. Haines and' J. B. Newsom, Serial. No. 60,502, led November 1'7, 1948. Details of.

3 the multifrequency pulsing receiving circuit are disclosed in Patent 2,332,912 granted October 26, 1943, to G. Hecht et al.

To consider rst a tandem connection employing a revertive pulse tandem sender or the type disclosed in the above-cited patent to Strickler as modifiedI by' the present disclosure, reference is made to Figs. 1, 2 and 3.

When the subscriber at substation l origi- 10 which of the two groups of trunks is seized. For

nates a call for a subscriber at an cnice whichv may be reached by way of the tandemoilice, substation Il is connected by line switchesv Hl!Y and |82 to a district junctor which, in turn,Y is connected over sender link switches |03. and |54 with. an originating subscriber sender. ThesubscriberV then dials the designation of the wanted line,

whereupon the sender connectsi with ay marker-v through the marker connector and the marker then connects with the district junctor: The sender transmits the office designation to the marker, which translates the designation into thenecessary information for selecting an outgoing trunk to the wanted oce, in this case a tandem oilice, and transmits to the sender instructions as to the manner in which the line designation is to be transmitted to that office. After'anidle trunk has been seized, switches |55 to |08 are operated by the markerr to connect the districtljunctor with the trunk, andthe marker andmarker. connector are released. The subscriber-sender'closes a bridge across the tipand ring conductors ofV the trunk to indicate to the equipment in the tandem oflice that it is ready toproceed.

The tandem trunk circuit thereupon passes a startsignal to the sender link and controller circuit (Fig. 2) which connects the trunk with an idle sender. pulses from the originating subscriber sendery to record the code'V for the terminating office. This code consists of two revertive pulse selections, namely; oflicebrush andolce group selections;

In'subscriber senders of early panel switching systemA ofces, there was provision for ve oice brush selections andten oiiice group selections, a combination providing for fty ofce codes. In senders in cross bar switching system offices, and in laterpan'el oice senders, provision is made for ten office brush selections and ten office groupselections, a combination providing one hundredoice codes. In the tandem sender disclosed herein means are provided to expand the selections -provided in theolder panel office type sender to one hundred oice codes, and further means areprovid'ed whereby the one hundredcode combinations selectable by either type of sender may be expanded to make available a total ofY three hundred code combinations to the marker;

In'. the case of panel office subscriber senders, the office brush selection is registered on the cnice brush register andthe office groupfselection is registered on the oice group register in the tandem sender of: Fig. 2. This code information is transmitted through the markerl connector (Fig. 2) to the'marker (Fig. 3) over the leads B|(2)l to,B4(2), (30(2) to G4(2), GB5(2) and GA5(2). IOne of the B|l(2) to BMD leads is grounded as determined by one of the live oflice brush selections received; One of the (7.6(2.) to (54(2) leads and the GBE (2) lead are grounded bythe corresponding ofce group selection 0 to 4; one of the G0(2) to G4(2) leads and the GA5(2) lead are grounded by the corresponding ofli'ce groupselection 5 to 9. Thus the five cnice-brush selections and-ten o'ce groupSelQQ" The sender then receives revertive 4 tions, in combination, provide for fty oflice codes. In'order to obtain fty additional office codes, two groups of tandem trunks are provided be- 5 tween the originating and tandem ofice, and provision is made in the tandem sender to connect ground to. one or the other of' thef BB5(2) or BA5'(2) leads in combination withthe previously mentioned B(2) to BMZ) leads, depending upon each of.y these groups of tandem trunks a relay 20.5 is" provided in the sender link and controller circuit. Only one such relay with alternate wiring has been shownin Fig. 2 for purposes of sim- 15 p licity; At the time thesender link seizes the sender, relay 2 Q2 is operated, by means not shown, thereby connecting' a plurality of leads through its contacts, among them leads 253 and 264. When one of the relays 295, associated with one 20 of the groups of tandem trunks, operates, ground is connected over a contact of relay 265, conductor2 5'to either conductor 263- or 234, through the No. l or No. 2 contact of operated relay 292, conductor 2|2 or 213, No. 4 or No. 5 contact of 251 operated relay SC(2), conductor 2M or 2|5,

winding of relay GB(2) or G-A(2) to battery. Thus, when the sender is seized, either relay GB(2) or GA(2) will be operated depending upon f whichof the twoV groups of tandem trunks is used.

301 When an ofce brush selection 0 to 4 is received a low 5 lead 2m is grounded in addition to one of the BMZ) to BMZ) leads previously mentioned. Lead 2M is multiplied at the contacts of relaysGB(2) and GA(2) If relay GAG) 3'5= is operated; the ground on lead 'Zl is conducted through the No. 2 contact of relay GAQ) to lead BA5(2). If relay @13(2) is operated, the ground on lead 20| is conducted through the No. 3 contact of relay GB(2) to lead BB5(2). Thus 4oA a total of one hundred code combinations can hundred code combinations over a single tandem' trunk group. In this case an oiiice selection-O to.4 grounds one-of the leads BMZ) to BMZ) and low 5 lead 20|, which, through the No. 3

contact of relay GB(2), grounds lead BB5`(2).

An ofce selection 5 to 9 grounds one of the leads BMZ) to BMZ) and high 5 lead 2li? which, through the No. 2 contact of relay (EB-(2), grounds lead BA5(2). If this trunk group, in subgroups of ten, were connected in the link circuit so as to operate relay GA(2) instead of relay GB(2), then the low 5 ground on lead 20| would cause the lead BA5(2) to be grounded and the high 5 ground on lead 207 would cause lead --BB5(2`) to be grounded, without changing the total number of codes available.

To obtain a maximum of three hundred revertive pulse office codes, by providing additional tandem trunk groups from an originating oflice,

65.V three additional relays Cil-10(2), GII|(2) and GH2(2)' are provided in the sender. One of these relays is operated on a given call, depending upon the subgroup assignment of the sender link of the tandem trunk originating the call, in

701. al manner similar to that already described for' 75.- ground; is connected to one of the three leads 209, ZIB, or 2H. This ground will be extended through the No. 3, 4 or 5 contacts of link relay 202 and No. 1, 2 or 3 contacts of sender relay SC(2) to the winding of relay GHO(2), CTI-IN2) or GH2(2), and to battery. Operation of relay (EI-10(2), GHI (2) or Cil-12(2) will connect ground, through its No. 2 contact, to the marker connector on leads, FS'(2), FSA(2), or FSB(2), respectively. Thus, these three grounded leads, each one in combination with the one hundred code combinations already described, make available a total of three hundred code combinations to the marker.

Referring to Fig. 3, each of these code combinations, transmitted to the marker through the marker connector, results in the operation of an individual route relay (not shown) in the marker. Ground on lead FSG), FSA(2) or FSB(2) will cause the operation of relay FS(3), FSA(3) or FSB(3). The operation of one of these three relays will connect the windings of ten relays TNO(3) to TN9(3), TNIO(3) to TNI9(3), or TN20(3) to TN29(3) respectively, to the TNO(3) to TN9(3) leads from the contacts of relays BB5(3) and BA5(3). One of these two relays BB5(3) or BAEGi), is operated by ground on the corresponding BB5(2) or BA5(2) lead from the marker connector. As above described, one of the B(2) to BME) leads to the contacts of the BB(3) and BA5(3) relays is also grounded. This ground will therefore operate one of the TNO(3) to TN29(3) relays.

The ten contacts of each of the TNO(3) to TN 29(3) relays are multipled through leads 0 to 9 to the contacts on the GB5(3) and GA5(3) relays. One of these relays is operated by ground on lead GB5(2) or GA5(2) from the marker connector and since one of the leads G0(2) to G4(2) is also grounded as previously described, it will be seen that a single ground lead is extended over one of the leads 0 to 9, and through the associated contact on that one of the relays TNO(3) to TN29(3) which is operated, to a single revertive pulse code cross-connection terminal 00 to 299. This terminal is connected to the winding of a route relay the contacts of which are wired or cross-connected in such a Way as to direct the marker in establishing the connection between the tandem trunk attached to the tandem sender and the terminating ofce corresponding to the office code registered in the sender.

To consider a tandem connection employing a multifrequency tandem sender, reference may be made to Figs. 4, 5, 6, 7 and 3. A more detailed discussion of the operation of the multifrequency tandem sender, disclosed in part herein, is contained in the above-cited copending application of W. T. Haines and J. B. Newsom.

It may be noted that the conductors leading from the revertive pulse sender of Fig. 2 through a marker connector in Fig. 2, and the conductors leading from the multifrequency pulse sender of Figs. 5, 6 and 7 through a marker connector in Fig. 2, are multipled together, respectively, between the marker connector and the marker.

Referring now to Fig. 4, when a calling subscriber at substantion 400 desires to place a call to a subscriber, operator or service position which may be reached by way of the tandem office, subscriber station 400 is connected to a tandem trunk circuit 402 by means of a cord circuit 40| at an operators position which is provided with a multifrequency pulsing keyset 403.

When the tandem trunk is seized it causes a sender link circuit 404 to connect the tandem receiving circuit which may be of the type disclosed in the above-cited patent to Hecht et al. Detailed circuits are shown only for those parts vof the sender concerned with the registration and translation of the cnice code digits.

The tip and ring leads (not shown) are connected into the sender and the multifrequency receiving circuit, which may be considered to be a part of the sender circuit. The operator at the originating ofice registers the code designation of the called line`by means of the keyset 403. Each digit keyed transmits a pulse of alternating current comprising two frequencies which, through the multifrequency receiving circuit, causes ground to be connected to a pair of the leads 0, I, 2, 4, 7, from the multifrequency receiving circuit shown in Fig. 5 to the digit-register relays shown in Figs. 5 and 6.

The olice codes used in this sender may be either two-digit or three-digit codes or a combination thereof. Two-digit codes comprise all combinations of tWo digits from 20 to 99, a total of eighty codes. Three-digit codes comprise all combinations of digits from 200 to 999, a total of eight hundred codes. Digits O and l are not used as the initial or A digit of regular oilice codes.

Three-digit office codes Consider rst the registration of three-digit codes. The rst or A digit is registered on two of the A digit-register relays A0(5) AI (5) A2 (5) A4(5), and ANS). The second or B digit is registered on the B-digit register comprising relays B0(6) to BHG); and the third or C digit is registered on the C-digit register comprising register relays 09(6) to 07(6).

The register relays are operated in pairs for each digit 0 to 9; the operated relays for each digit being as follows:

Receiver A Digit B Digit C Digit Number Keyed Gfsed Relays Relays Relays 4, 7 A4, A7 B4, B7 O4, C7 0, l A0, Al B0, B1 C0, Cl 0, 2 A0, A2 B0, B2 C0, C2 l, 2 Al, A2 Bl, B2 C1, C2 0,4 A0, A4 B0, B4 G0, C4 l, 4 A1, A4 Bl, B4 Cl, C4 2, 4 A2, A4 B2, B4 C2, C4 0, 7 A0, A7 B0, B7 C0, C7 1, 7 A1, A7 B1, B7 Cl, C7 2, 7 A2, A7 B2, B7 C2, C7

The registration leads from the multifrequency receiving circuit are transferred successively from digit to digit by means of a walking circuit consisting of a pair of relays per digit: relays AA(5) and AB(5) for the A-digit register, relays BA(6) and BB(5) for the B-digit register, and relays CA(9) and CBGB) for the C-digit register. 'I'hese pairs of relays are all operated before registration starts and are released sequentially as registration proceeds.

The operation of off-normal relay ON(5) (by means not shown) connects ground through the No. l contact of unoperated relay ALI(5) to the windings of relays AB(5) and AA(5) in series, and to battery. These relays both operate and lock, through the No. 3 contact of relay AB(5), to ground at the contact of relay ON(5) Relay AB(5), in operating, closes ground over conductor W(5) to the windings of relays BB(S) and BA(6). These relays operate and in turn extend ground on conductor W(5) to operate relays CB(6) and CA(B).

When the multifrequency receiver, Fig. 5, reoei-ves two frequencies corresponding to the rst office code digit, it grounds lead H(5) and two ofthe leads I! to l, except the combination I) and I, corresponding to the digit 1, which is never used as the rst digit of an office code. The initial ground on two leads, leads I and I for instance, operates the two corresponding register relays in the A-digit register, in this case relays AI(5) and A7(5). Any pair of register relays, except relays A(5) .and AI (5) in combination, will provide a path for the ground on lead H(5) to shunt down relay AB(5), but continue to hold relay AA(5) operated. The holding windings of the two operated relays, any two except AIME) and AI (5) in combination, are connected in parallel through the No. 2 contact of operated relay AA(5), No. l contact of released relay AB(5), primary winding of relay TM5) back contact of relay CKA(5), to ground on lead K(5) in the multifrequency receiver circuit. Relay CKA(5) was released a few milliseconds following the receipt of the two frequencies by the receiver at the same time the receiver connects ground on the J -L loop, which includes a back contact of relay TM5) to lock the receiver relays operated, even though the multifreduency pulses from the originating end have ceased. Relay T(5) is a marginal relay which will not operate in series to battery on only one register relay locking Iwinding, but relay TM) will operate to battery through the locking windings of two register relays in parallel.

When relay Til (5) operates, it locks to a ground in the multifrequency receiver over lead J (5) and opens lead L(5), which is the locking path for the receiver channel relays. At this time if the multifrequency pulses have ceased, or otherwise when the multifrequency pulses do cease, the receiver channel relays release, which removes ground from lead 11(5) and reconnects ground to lead M(5). Removal of ground from lead 1I(5) releases relay AA(5), which transfers the IJ to 'I leads to the B-digit register relays, BMG) to BHG), through front contacts of the previously operated relay BA(5). Lead H(5) is also transferred to the BA(5) relay. The placing of ground on lead M(5) reoperates relay CKA(5).

Registration of subsequent digits on the B and C-digit registers takes place in a similar manner except that no distinction is made for the combined operation of the 0 and I relays corresponding to the digit l; and except that the ground closure on lead H(5) does not depend on the prior operation of one of the register relays, but is applied immediately to shunt down the BB(6) or CB(6) relays simultaneously with the operation of the register relays. The numerical digits following the oice code are registered on thousands, hundreds, tens, units-, .and stationsdigit registers, not shown.

Register relays A0(5) AI (5), A'Z(5) ,'A4(5) and A1(5) operate auxiliary register relays AUA(5), AIA(5), A2A(5), A4A(5) and A'IA(5), respectively, to provide suflicient contacts for later switching operations.

When a three-digit ofce code is registered on the A, B- and C-digit registers, relay DST(5) is operated over leads (not shown) from the C- digit register. Relay DST(5), in operating, connects ground over conductor BTR(5) to operate relay BTR('I) and also, by means not shown, causes the marker connector (Fig. 2) to func- 8 tion to connect the leads from the sender register relays into the marker.

Any pair of A-digit register auxiliary relays, ABA(5) to A'IA(5) operated to register the digits 0 to 4, connects ground to one of the leads B0(5) to B5(5) through the marker connector (Fig. 2) to the marker (Fig. 3) through the No. 9, No. 7, No. 6, No. fl, or No. 2 contacts of operated relay BTR('I), and the No. 8, No. 14, No. 5, No. 3, or No. 1 contacts of unoperated relay '1XA('I).A In addition lead BBEH) to the marker is connected to ground through the No. 10 contact 0f relay TXACI) and through the No. l1 contact of relay ABEG), which is operated when an A- digit less than 5 is registered.

Any pair of A-digit register auxiliary relays, AUA(5) to AIA(5), operated to register digits 5 to 9 also connects ground to one of the leads B0(5) to BME) to the marker, but lead BA5('I) is grounded instead of lead BB5(1), since relay AB5('I) is not Operated when an A digit 5, or greater, is registered.

Similarly, the digits 0 to 4 registered on the B-digit register, one of the leads DMG) to DME) is grounded, together with lead DBMS). For any digits 5 t0 9, one of the leads DMG) to DMG) is grounded together with lead DA5(6).

1n like manner, for the C-digit register, one

of the leads GMES) to GMS) is grounded, to-A gether with either lead GB5(6) or GA5(5) depending on whether the digit is less than 5, or 5 or greater.

Lead LA(5) to the marker is grounded on all regular office codes by ground at the No. 1 contact of relay IIB(5) which operates only on socalled TX codes to be described hereinafter.

In the marker, Fig. 3, lthe ground on lead LA(5) is conducted through the winding of relay YLA(3) to battery. Relay LAGE), in operating, closes ground from grounded lead DB5(6) or DA5(5) through the No. 2 or No. 1 contacts of relay LAG) to operate relay DB5(3) or DA5(3). The ground placed on lead BB5(5) or BA5(5) in the sender is conducted to the marker through the marker connector to operate relay BB5(3) or relay BA5(3). With either relay BB5(3) or relay BA5(3) operated, and with ground on one of the leads B(l(5) to BME), ground will be placed on one of the leads TNMS) to TNMS) in accordance with the digit registered in the A-digit register in the sender. This ground on one of the leads TN!)(3) to TN8(3) is conducted to the contacts of relays DB5(3) and DA5(3) in multiple. If relay DBMS) is operated, the ground is conducted through one of the contacts of that relay to the corresponding lead 2H(3) to 9I1(3) to operate one of the 2H(3) to Sil-1(3) relays. If relay DA5(3) is operated, the ground is conducted through one of the contacts of that relay to the corresponding lead 2H'(3) to 9H(3) to operate one of the 2H(3) to 9H(3) relays. It may be noted that the connections for lead TNO( 3) at the contacts of relays DB5(3) and DA5(3) are connected to terminal VC to which the vacane code route relay is connected, since the digit 0 is never used as the first digit of an oice code. The connections for lead TNI(3) at the contacts of relays DB5(3) and DA5(3) are utilized in the case of service codes to be hereinafter described.

The ground in the sender on one of the leads DMG) to DMS) is conducted through the marker connector to operate the corresponding relay Dll(3) to DMB).

The ground placed on lead GB5(6) or GA5(6) in the sender is conducted to the marker to operate relay GB5(3) or GA5(3). With one of these relays operated, and with ground on one of the leads GMG) to G1HB), ground will be placed on one of the leads to 9 in accordance with the digit registered in the C-digit register in the sender. This ground is conducted to the contacts of relays DMS) to DMS) in multiple. That ground will then be conducted through the associated one oi the ten contacts of the operated relay D0(3) to D4(3), over one of the leads 0 to 49 and to the contacts of relays 2H(3) to 9H(3) in multiple. Each of the relays 2H 3 to 9H(3) is provided With 50 contacts. Therefore, the ground on one of the leads 0 to 49 is .conducted through the associated contact of that one of the relays 2H(3) to 9H 3) which is operated, and is then conducted to one of the oice code terminals 200 to 299. Each of these terminals is connected to the winding of an individual route relay which is arranged to direct the marker in establishing the connection between the tandem trunk associated with the tandem sender and the terminating oflice corresponding to the oce code registered in the sender.

In this manner the 800 possible oflice codes in the sender, using the digits 2 to 9 for the A- digit any any digit 0 to 9 for the B and C- digits may be connected to operate an independent route relay in the marker. For example, assume that the ofce code is 259. Then the sender will ground leads B2(5), BB5(5), DMG), DAMS), GMS), GA5 6) and LA'(5). In this case, ground on lead B2(5) through contacts of operated relay BB5(3) and operated relay DAMS) will operate relay 2H(3), which controls code points 250 to 299. Ground on lead GMS) through contacts of operated relays GA5 3 and DMS) Will be connected to the associated contact of the ZH( 3) relay, which is connected to the terminal corresponding to the code 259.

Two-digit oice codes Consider now the registration of two-digit ofiice codes by the multifrequency sender shown in Figs. 5, 6 and 7. Any A-digit 2 to 9 may be used as a two-digit oilice code index. For such initial digit or digits, the corresponding cross-connection terminals L2('l) to L90) are connected to terminal TDG). When a two-digit index is registered on the A-digit register, Fig. 5, ground from the auxiliary A-digit register relays, AOA(5) to ATAG), is conducted over one of the leads B0(5) to BMS) through one of the back contacts of unoperated relay BTR(1) and through either a back or front contact of relay AB5 1) to the cross-connection terminal TDG). Terminal TDG) is connected over lead TDG) through the No. 1 contact of relay HA 5), over conductor TDW(5) to the winding of relay TDG), which operates and locks to off-normal ground. Relay AB5(1) is preoperated by offnormal ground supplied through the contact of operated relay ON( 5). Since this operating path is under the control of the A-digit register relays, relay AB5 1 remains operated if the A digit registered is 0 to 4, but is released if the A digit is 5 to 9. Relay AB5(1) is fast releasing so that it will be released, if it is going to release, before the operating ground for relay TDH) is supplied by the operation of the auxiliary A-digit register relays AOA(5) to A1A(5).

The B digit of a two-digit oice code is regand directory positions, etc.

istered on the B-digit register; but the operation of relay 'I'D(1) breaks, at its No. 1 contact, the locking path for the CA(6) and CB(6) walking relays, and the release of these relays results in the effective bypassing of the C-digit register so that the next or thousands digit will be properly registered in the thousands digit register. The remaining numerical digits are registered in their corresponding registers.

Thus both two-digit and three-digit office codes may be used. Ii all A digits are cross-connected for two-digit codes by connecting all terminals L2(l) to LSU) to the TDG) terminal, then relay TDC!) is operated on all oice codes and only two-digit codes are used, namely, 20 to 99, a total of codes. Y

Relay TDG) in operating, closes a circuit through its No. 3 contact to operate relays TXB) and TXC(7). Leads D(6) to DMS) and DB5(6), from the B-digit register relays, Fig. 6, are transferred by the operation of relay TXBU) so that these leads are disassociated from leads D00) to DMT) and DB5('1), and are connected to leads G00) to GMT) and GB5('I), respectively, to the marker connector. Operation of relay TXCU) disassociates leads GMS) to GMG) GA5(6) and GB5(6) from leads G00) to G40), GA5('I) and GRECI), and transfers lead DA5(6) from lead DAB ('l) to lead GA5(7). The operation of relay TDH) connects, at its Nos. 4 and 5 contacts, ground to leads DGH) and DB5(1), which is the equivalent of the registration of the digit 0 on the B-digit register. Thus a two-digit code, 25 for example, is transmitted as code 205 to the marker. Therefore, a two-digit oice code is translated in the marker in the same fashion as is a three-digit oiice code except that only those oiiice code route relay terminals 200 to 999, associated with relays 2H(3) to 9H' (3) which have 0 as their middle digit are available for two-digit codes, i. e. 200 to 209, 300 to 309, etc.

Service codes Service codes are those used by toll operators to obtain special connections such as to the toll information board, to the toll test board, to route Service codes are generally of the form DX in which D may be any digit except 1, and X any digit 0 to 9, and are distinguished from other codes by the fact that they are always prexed by a certain preselected digit, herein presumed to be the digit 1.

When a service code, to 109, or 120 to 199, is received, the initial digit l is registered by the operation of the counting relays ||A(5) and HA(5), and the two digits of the service code proper are registered on the A- and B-digit registers. When the digit 1 is received by the sender as an initial or A digit, the receiver grounds leads 9(5) and H5) to operate the AWS) and Al (5) register relays. With these two relays operated, a ground is connected from the No. 1 contact of relay Al(5), No. 2 contact of relay AMS), No. 4 contact of unoperated relay IIA(5), winding of relay IIA 5 to battery, thereby operating relay IIA(5). The multifrequency receiver connects ground to lead.I-I(5) as usual, but this lead is not connected through contacts of either relays Ail(5) to Al(5) to advance the walking circuit by sliunting down the AB(5) relay.

Battery through resistance Y(5), equivalent to two register relay locking windings in parallel, is connected through the No. 3 contact of op- 11 erated relay IIA(5), No. 6 contact of unoperated relay I TA' (5) No. 1 contact ofY relay AM5) Winding of relay TM5) contact of relay CKA(5), to ground on lead K(5) in the multifrequency receiver, and relay TM5) operates. The operation Vof relay TM5) allows the channel relays in the multifrequency receiver to release, and they release relays AM5) and AI (5). This permits relay HA(5) to operate over a path from ground at the contact of off-normal ground relay ON(5) No. 2 contact of relay IIA(5) windings of relay HA(5) and IIA(5) in series, to battery. These two relays thus lock operated in series to ground over the No. 2 contact of relay ON(5).

, The second digit received, or the rst digit of the service code proper, may be any digit except the digit 1. The registration of this digit is retained on the A-digit register relays, and the walking circuit is advanced so that the third received digit will be registered on the B-digit l register. As is apparent from the circuit, this dierence in operation is a result of the fact that the ground on lead II(5) is closed through in all cases except in the operation of the AM5) and Ai (5) relays in combination, and no locking path is provided for these two relays when they are operated together.

Relay llA(5), in operating, connects ground, at its Nos. 2 and 3 contacts, to leads TBI (5) and BB5(5) which are extended as leads BMT) and BBMT) to the marker connector, and represent the digit 1. When` the third received digit is registered, relay DST(5) operates, through a path not shown, and causes the marker connector to connect the sender with an idle marker. With relays DST(5) and IIA(5) operated, ground is connected from the contact of relay DSTGS), through the No. 1` contact of relay HA(5) to lead TXA(5) to operate relay TXACT), and through the No. 2 contact of unoperated relay TDG) to operate relays TXB (T) and TXC( T) The operation of relay TXA(T) causes leads BMS) to BME), from the A-digit register and through the contacts of operated relay BTR(T),

to be disassociated from the B-s'eries leads to the marker connector upon the opening of the Nos. 8, 14, 5, 3 and 1 contacts of relay TXA(T), and to be connected to the D-series leads to the marker connector upon the closure of the Nos. '7, 13, 6,

4, and 2 contacts of relay TXAVT). Similarly,

operation of relay TXB(T) and TXC(T) causes the B-digit register leads DMG) to DM) DAMS) and DBMS) to be connected to the G-series leads to the marker connector and disconnects the C- digit register leads GMS) to GMG), GAMB) and GBME) at the Nos. '1, 6, 5, 4, 3, 8, and 9 contacts of relay TXC(T). Thus, in transmitting the service code designation to the marker, the initial digit 1 is transmitted over the B-series leads normally associated with A-digit register, the next digit, which is registered on the A-digit register, is transmitted over the D-series leads normally associated with the B-digit register, and the last digit of the service code, which is registered on the B-digit register, is transmitted over the G-series leads normally associated with the C-digit register. In other words a two-digit service code prefixed by the digit "1 is transmitted to the marker, Fig. 3, as a three-digit code having l as an initial digit.

In the marker, Fig. 3, the ground on lead DBMT) or DA5(T), resulting from the registration in the sender A-digit register of a digit less than 5 or 5 or greater, respectively, is conducted through the No. 2 or No. 1 contact of op- 'digit as the case may be.

erated relay LA(3) to' operate either relay DBMS) or relay DA5(3). Relay BB5(3) is operated by the ground on lead BBMT) The ground on lead Bl (T) is then conducted through the associated contact of operated relay BBMS) to lead TNT (3) over which it is conducted to the associated contacts of relays DBMS) and DA5(3), in multiple. If relay DBMS) has been operated, the ground will be conducted over lead IH(3) to operate relay TH(3). If relay DA5(3) has been operated, the ground Will be conducted over lead IH(3) to operate relay 1H(3).

The ground on one of the leads DMT) to DMT), depending on the digit registered in the sender A-digit register, serves to operate one of the relays DMS) to DMS). Relay GB5(3) or GA5(3) is operated from the ground placed on lead GB5(T) or GA5(T) depending on whether a number less than 5 or 5 or greater was registered in the sender B-digit register. Then the ground on one of the leads GMT) to GMT) will be conducted through tne associated contact of operated relay GB5(3) or GAME), over one of the leads to 9, through the associated contact of that one of the series of relays DMS) t0 DMS) which is operated, over one of the leads i! to fig, over the associated contact oi operated relay IH(3) or IH (3) to the proper one or the service operator code terminals 10Q to 199 to operate the selected route relay. For example, if a service code 49 prefixed by digit 1, is received at the sender, the digit "1 will be registered on relays MM5) and IIA(5) and leads BB5(T) and BUT) will be grounded. The digit e will be registered on A- digit register relays AM) and AME) resulting in the subsequent grounding of leads DB5(1) and DMT). The digit 9 will be registered on the B-digit register relays BMG) and BN), resulting in the subsequent grounding of leads GAMT) and GMT) Therefore, in the marker, relays LA(3), BB5(3), DBMB), and GA5(3) will be operated. The ground on lead Bl (T) will be condcted through the associated contact of operated relay BB5(3), over conductor TNHS), through the associated contact of operated relay DB5(3), over conductor 15(3) to operate relay IH(3). Ground on lead DMT) Will operate relay DMS). The ground on lead GMT) will be conducted through the associated contact of operated relay GA5(3) over conductor 9, through the associated contact of operated relay DMB), over conductor 49, through the associated contact of operated relay IH(3), to service operator code terminal |49.

Special service codes Special service codes, herein also referred to as TX codes, may be either two-digit or three-digit codes prexed by the digits 11, i. e., HEX or llEXX codes, where represents any digit from 0 to 9, and E represents any digit except 0.

TX codes are used principally in the completion of delayed toll calls. In'the case, for instance, of a person-to-person call inY which the called party is unavailable, the operator may ask that the called party be requested to call the toll or long distance operator at the city where the call has originated, and designate this operator by the name of the city and a number, two-digit or three- When the called party later asks his own operator to connect him with the toll operator EX or EX I in the distant city, his operator will dial or key the digits "11EX or MEXX over a toll line. This will connect the originating oice, Who will then complete the call to the original calling subscriber.

Certain TX codes are used for special purposes such as establishing toll conference connections, connections to charge quotation operators, and so on. f

When a TX code preceded by the digits 11 is received, the tWo successive digits l are registered on the IIA(5), HA(5), |IB(5), and I|B(5) counting relays. The following two or three digits of the TX code proper are registered on the A- and B, or on the A, B- and C-digit registers, respectively.

The first received digit "1 is registered on relays IIA(5) and IIA'(5) as above described. The second received digit l operates relays MM5) and AI (5) as before. Operation of these relays closes a path from ground at the No. l Contact of relay AI (5), No. 2 contact of relay AME), No. 5 contact of operated relay HA(5), No. 4 contact of relay l IB(5), Winding of relay i IB(5), to battery. The consequent operation of relay IIB(5) results in the connection of battery through resistance Y(5), through the No. l contact of relay HB(5), No. 5 contact of unoperated relay |IB(5) No. 1 Contact of relay )45(5), winding of relay T(5), contact of relay CKA(5), to lead K() which is grounded in the multifrequency receiver. Relay TM5) in operating, releases relays AU(5) and A! (5), as described hereinbefore. The release of relays AMS) and A! (5) disables the shunting path around the Winding of relay HB(5), and relay HB( 5) thereby operates over a path from battery, Winding of relay ||B(5), winding of relay HB(5), No. 3 contact of relay l IB(5), to ground at the contact of relay ON(5). Relay IIB(5), in operating, closes, through its No. 7 contact, lead H(5) to the Winding of relay AA(5) independently of which or the A-digit register relays is operated, and thereby also prepares a shunting path around the Winding of relay AB(5). Relay IIB(5), in operating, also provides an independent path for the locking windings of A-digit register relays MM5) and AI (5). Therefore, the next digit to be received, Which will be the rst digit of the TX code proper, will be registered and locked on the A-digit register even if it be the digit 1, and the Walking circuit will be advanced. The register circuits of the sender operate in the normal fashion thereafter, registering the second digit of the TX code proper on the B-digit register and, if three-digit TX codes are used, registering the third digit of the TX code proper on the C-digit register.

In the case of two-digit TX codes, the resulting transmission to the marker is similar to that in the case of two-digit service codes; in the case of three-digit TX codes, the resulting transmission to the marker is similar to that in the case of three-digit ofce codes. Therefore, means must be provided to enable the marker to distinguish TX codes from other types of codes. This is accomplished upon the operation of relay HB(5) when the second digit 1, preiixing a TX code, is received. Relay |IB\(5), in operating, breaks, at its No. l contact, the previously existing cone nection between ground and lead LAGE), and es* tablishes, at its No. 2 contact, a connection from ground to lead EA(5). Ground on lead LA(5) indicates to the marker that an office or service code is being transmitted from the sender, and ground on lead EA( 5) indicates that a TX code is being transmitted.

Although the use of either two-digit or threedigit TX codes is contemplated, it may benoted that in the present disclosure no provision is made for the combined use of these two types of TX codes. When three-digit TX codes are used, the T option wiring at relay IIB(5) is used, and when two-digit TX codes are used, the S option Wiring is used. It may be noted that the S option wiring comprises the placing of shunts around the circuits through the Nos. 1, 2 and 3 contacts of relay IIB(5). Since relay iIB(5) is unoperated except in the registration of TX codes, Whether S or T option Wiring is used is immaterial in the registration of oilice or service codes. For two-digit TX codes, the use of the S option shunts around the contacts of relay ||B(5) causes the circuits to operate in the same fashion as that described for service codes. Since the Nos. l, 2 and 3 contacts of relay I|B(5) are shunted, the operation of relay IIB(5) is ineffective to break the circuits through these contacts, ground is placed on leads IBI (5) and BB5(5) and relays TXA), TXBCI) .and TXCH) are operated as before described.

Therefore, the digit l, is transmited over the B-series leads, the rst digit of the TX code proper, which is registered on the A-digit register, is transmitted over the D-series leads, and the second digit of the TX code proper, which is registered on the B-digit register, is transmitted over the G-series leads to the marker. In the marker, Fig. 3, the ground on lead EA(5) will serve to operate relay E`A(3). The ground on lead DB5( l) or DA5(1) Will be conducted through the No. 2 or No. 1 contact of relay EA(3) to operate relay TXB5(3) or TXA5(3). The ground on lead BBE (l) serves to operate relay BB5(3) The ground on lead Bl (l) is conducted through the associated contact on operated relay BB5(3), over conductor TN {(3), through the associated contact of that one of the relays TXB5(3) or TXA5(3) which is operated, over lead TXI (3) or TX|(3), to operate relay TXI(3) or TX|'(3).

The ground on one of the leads DM?) to DMD, depending on the value of the digit registered in the sender A-digit register, serves to operate the associated one of the relays Dil (3) to D11( 3). The ground on lead GA5('!) or GBECI) serves to operate relay GA5(3) or GB5(3). The ground on one of the leads GBV!) to GMT), depending on the Value of the digit registered in the sender B-digit register, is conducted through the associated contact Yof operated relay GB5(3) or GBA(3), over one of the conductors il to S, through the associated contact of that one of the DB (3) to D11-(3) relays which is operated, over one of the leads o to 49, through the associated contact of operated relay TXI (3) or TXI(3) to the associated TX operator code terminal 00 to 99, which is connected to a route relay.

For example, if two-digit TX codes are used and the code 38 prexed by the digits ll received, registration of those digits in the multtl frequency sender Will result in ground being placed-on leads EAG) BEECH), Bid), 1035), DSG), GA5('!), and G36). Relays EA(3), TXB5C3), BB5(3), and GA5(3) will be operated. The ground on lead BH1) will. be conducted through the associated contact of relay BB5(3), over lead TN I (3) through the associated contact of relay TXB5(3), over lead TXI (3), to operate relay TX! (3). The ground on lead D3 (l) Will operate relay D3(3). The ground on lead G30) will be conducted through the associated com tact of relay GA5(3), over lead 8, through the associated contact of operated relay D3(3), over lead 38, through the associated contact of oper-.

15 ated relay TXI(3) to the TX operator code ter- Ininal 38. i

For three-digit TX codes T option wiring is used at the HB'(5) relay. Therefore with relay I IB'(5) operated, the previously traced energizing cii'cuits for relays TXMD, TXBl) and TXCU) are interrupted at the No. l contact of relay IIB'(5). Thus the leads from the A, B- and C-digit registers are connected to the marker B-series, D-series and G-series leads, respectively, in the same fashion as for regular oiiice codes, and, therefore, a three-digit TX code is transmitted to the marker in the same manner as is a three-digit office code. The above discussed grounding of the EA() lead again serves as a means for the marker to distinguish TX codes from office or service codes.

In the marker, Fig. E, the ground on lead EA(5) willserve to operate relay EAGE). The ground on lead DBMS) or DA5 l), depending on whether the digit registered in the sender B- digit register is less than 5 or 5 or greater, will be conducted through the No. 2 or No. l contact of relay EA(3) to operate relay TXBMS) or TXA5(3). The ground on lead BB5(l) or Bifl), depending on Whether the digit registered in the sender A-digit register is less than 5 or 5 or greater, will operate relay BB5(3) or BA5(3). The ground on one of the leads BSC!) to BM?) is conducted through the associated contact on operated relay BB5(3) or BAMS) over one of the conductors TNMS) to TNSMS), through the associated contact of that one of the relays TXB5(3)or TXA5 3 which is operated, over one of the leads TXi (3) to TX3(3), to operate the associated one of the relays TXi (3) to TX3(3). The ground on one of the leads DDG) to B4G), depending on the value of the digit registered in the sender B-digit register, serves to operate the associated one of the relays DMS) to DMB) The ground on lead GBM?) or GAM?) serves to operate relay GB5(3) or GA5(3). The ground on one of the leads GM?) to GM), depending on the value of the digit registered in the sender C-digit register, is conducted through the associated contact of operated relay G1356) or GAMS), over one of the conductors to 9, through the associated contact of that one of the DMS-5) to DMS) relays which is operated, over one ci the leads li to 49, through the associated contact of that one of the relays TX! (3) to TXl (3) which is operated, to the associated TX operator code terminal c to 399, which is connected to a route relay. Thus, the three-digit special service or TX code has been translated into a circuit path whereby a single route relay corresponding tothis code may be operated to control the extension of the connection between the tandem trunk and the desired special service position.

The above description of the invention is purely illustrative, and the association of the invention with the disclosed cooperating equipment is but representative and is not to be interpreted in a limiting sense.

What is claimed is:

1. In a telephone system, an originating oilice,

a tandem cnice, switching equipment at each of said ofrlces, a trunk extending between eriginating oflice and said tandem ofce, a piurality of service positions connectabie to said trunk through the switching equipment at said tandem cfiice, a sender in said tandem oice associable with said trunk for registering the designation of any of said service positions, and a marker in said tandem oiiice responsive to the code digits registered in saidsender for controllingthe extension of a connection from said trunk to the designated one of said service positions, said marker comprising iirst means responsive to the registration in said sender of a service code, and second means operable in response to said :drst means for translating the service code digits registered in said sender and for transmitting an indication for actuating means to control the extension of said connection.

2. In a telephone system, an originating ciiice, a tandem oiiice, a plurality of terminating offices, switching equipment at each of said oiices, a trunk f extending between said originating oiiice and said tandem office, a plurality of special service positions connectable to said trunk through the switching equipment at said tandem office, a sender in said tandem oice associable with said trunk for registering the designation or any of said terminating offices or of any of said special service positions, and a marker in said tandem oiiice responsive to the code digits registered in said sender for controlling the extension of a connection from said trunk to the designated one of said terminating offices lor of said special service positions, said marker comprising iirst means selectively operable in response to the registration in said sender of an office code or a special service code, and second means selectively operable in response'to said first means for translating the code digits registered in said sender and for transmitting an indication for actuating means to control the extension of a connection to either a terminating oiiice or to a special service position.

3. In a telephone system, an originating oiice, a tandem office, switching equipment at each ci said oiiices, a trunk extending between said originating oice and said tandem oil-ice, a plurality of service positions connectable to said trunk through the switching equipment at said tandem oiiice, a sender in said tandem office associable with said trunk for registering the designation of any of said service positions, and a marker in said tandem oiiice responsive to the code digits registered in said sender for controlling the extension of a connection from said trunk to the designated one of said service positions, said marker comprising first means for translating an indication of the registration in said sender of a certain digit prexing said service code digits and an indication of the value of the first service code digit and for transmitting an indication thereof, second means for translating an indication of the value of the irst service code digit and an indication of the value of the second service code digit and for transmitting an indication thereof, and means for translating the indications transmitted by said first and said second means and for transmitting an indication for actuating means to control the extension of said connection.

, 4. Ina telephone system, an originating oiiice, a tandem oice, switching equipment at each of said orlices, a trunk extending between said originating oliice and said tandem office, al plurality of service positions connectable to said trunk through the switching equipment at said tandem office, a sender in said tandem oice associable with said trunk for registering the designation of any of said service positions, and a marker in said tandem ofce responsive to the code digits registered in said sender for controlling the extension of a connection from said trunk to the designated one of said service positions, said marker comprising iirst means selectively operable in response to the value of the first of the service code digits for translating an indication of the registration in said sender of a certain initial digit preceding said service code and for transmitting an indication thereof, second means selectively operable in response to the value of the rst and of said service code digits for translating an indication of the value of the second of said service code digits and for transmitting an indication thereof, and means selectively operable in response to the indication transmitted by said rst means for translating the indication transmitted by said second means and for transmitting an indication for actuating means to control the extension of said connection.

5. In a telephone system, an originating cnice., a tandem office, switching equipment at each of said offices, a trunk extending between said originating oince and said tandem office, a plurality of service positions connectable to said trunk through the switching equipment at said tandem ofiice, a sender in said tandem ofiice associable with said trunk for registering the designation of any of said service positions, and a marker in said tandem oiice responsive to the code digits registered in said sender for controlling the extension of a connection from said trunk to the designated one of said service positions, said marker comprising first means responsive to the registration of a service code in said sender, secondmeans responsive to the registration in said sender of a certain initial digit preceding said service code for transmitting an indication of said certain digit, third means selectively operable in response to the operation of said first means and to the value of the first service code digit for translating said indication from said second means and for transmitting an indication thereof, fourth means responsive to the value of the second of said service code digits for transmitting an indication thereof, fifth means selectively operable in response to the value of the first of said service code digits for translating said indication from said fourth means and for transmitting an indication thereof, sixth means responsive to the indication transmitted by said third means for translating the indication transmitted by said fifth means and for transmitting an indication thereof, and means actuated by said indication transmitted by said sixth means for controlling the extension of said connection.

6. In a telephone system, an originating office, a tandem office, switching equipment at each of said offices, a plurality of trunks extending between said originating office and said tandem office, a plurality of service positions connectable to said trunks through the switching equipment at said tandem oflice, each of said positions being designated by a two-digit service code prefixed by a preselected digit, a sender in said tandem office associable with any of said trunks for registering the designation of any of said service positions, and a marker in said tandem office responsive to the code digits registered in said sender for controlling the extension of a connection from one of said trunks to the designated one of said service positions, said marker comprising first means responsive to the registration of a service code in said sender, second means responsive to the registration in said sender of said preselected digit prefixing said service code and for transmitting an indication thereof, third means operable in response to the operation of said first means and to the registration in said sender of a first service code digit greater or less than a preselected value for translating theA indication transmitted by said second means and for transmitting an indication thereof, fourth means responsive to the value of the second service code digit registered in said sender to transmit an indication thereof, fifth meansv for transf lating an indication of the value of the first service code digit and said indication transmitted by said fourth means and for transmitting an indication of the combination of said first and said second service code digits, sixth means for translating the indications transmitted by lsaid third means and said fifth means and for'transmitting an indication of the combination of said first and said second service code digits and said preselected digit preiixing said service code digits, and means responsive to the indication transmitted by said sixth means for controlling the extension of said connection.

7. In a telephone system, an originating ofce, a tandem office, switchingequipment at each .of said oiiices, a trunk extending between said originating office and said tandem office, a plurality. of special service positions connectable to said trunk through the switching equipment at said tandem office, a sender in said tandem office associable with said trunk for registering the designation of any of said special servicepositions, and a marker in said tandem office responsive to the code digits registered in said sender for controlling the extension of a connection from said trunk to the designated one of said special service positions, said marker comprising first means responsive to the registration in said sender of a special service code, and second means operable in response to said first means for translating the special service code digits registered in said sender and transmitting an indication for actuating means to control the extension ofsaid connection.

8. In a telephone system, an originating office, a tandem onice, switching equipment at each of said oces, a trunk extending between said originating oice Vand said tandem office, a plulrality of special service positions connectable vto vsaid trunk through the switching equipment at saidv tandem office, a sender in said tandem ,office associable with said trunk for registering the designation of any of said special service positions, and a marker in saidv tandem office responsive to the code digits registered in said sender for controlling the extension of a connection from said trunk to the designated one of said special service positions, said marker comprising first means responsive to the registration in said sender of a special service code, second means operable in response to said first vmeans for translating an indication of the registration in said sender of a certain digit prefixing said special service code digits and an indication of the value of the first special service code digit and for transmitting an indication thereof, third means for translating an indication of the value of the first special service code digit and an indication of the value of the second special service code digit and for transmitting an indication thereof, and means for translating the indications transmitted by said second and said third means and for transmitting an indication for actuating means to control the extension of said connection.

9. In a telephone system, an originating office, a tandem office, switching equipment at each of 19 Y said ofIi'ces, a trunk extending between said originating and said tandem ofces, a plurality of special service positions connectable to said trunk through the switching equipment at said tandem oiice, each of said positions being designated by a two-digit special service code prefixed by two preselected digits, a sender in said tandem oiiice associable with any of said trunks for registering the designation of any of said special service positions, and a marker in said tandem office responsive to the code digits registered in said Asender for controlling the extension of a connection from said trunk to the designated one of said special service positions, said marker comprising iirst means responsive to the registration in said sender of the two preselected digits preiixing a special service code, second means responsive to the registration in said sender of the preselected digits prexing a special service code for transmitting an indication thereof, third means selectively operable in response to the operation of said irst means and to the value of the rst of the special service code digits for translating said indication from said second means and for transmitting an indication thereof, fourth means responsive to the Value of the second of said special service code digits for transmitting an indication thereof, fifth means selectively operable in response to the value of the rst of said special service code digits for translating said indication from said fourth means and for transmitting an indication thereof, sixth means responsive to the indication transmitted by said third means for translating the indication transmitted by said fth means and for transmitting an indication thereof, and means actuated by said indication transmitted by said sixth means for controlling the extension of said connection.

10. In a telephone system, an originating ofce, a tandem ofi-ice, switching equipment at each of said ofiices, a trunk extending between said originating oce and said tandem oice, a plurality of special service positions connectable to said trunk through the switching equipment at said tandem oce. a sender in said tandem ofiice associable with said trunk for registering the designation of any of said special service positions, and a marker in said tandem office responsive to the code digits registered in said sender for controlling the extension of the connection from said trunk to the designated one of said special service positions, said marker comprising rst means responsive to the registration in said sender of a special service code, second means operable in response to said rst means for translating an indication of the value of the rst digit of said special service code and an indication of the value of the second digit of said special service code and for transmitting an indication thereof, third means for translating an indication of the value of the second digit of said special service code and an indication of the value of the third digit of said special code and for transmiting an indication thereof, and means for translating the indications transmitted by said second means and said third means and for transmitting an indication for actuating means' to control the extension of said connection.

1l. In a telephone system, an originating ofce, a tandem oice, switching equipment at each of said oflices, a trunk extending between said originating office and said tandem office, a plurality of special service positions connect-able to said trunk through the switching equipment at said tandem ofce, each of said positions being designated by a three-digit special service code prexed by two preselected digits, a sender in said tandem office associable with said trunk for registering the designation of any of said special service positions, and a marker in said tandem oice responsive to the code digits registered in said sender for controlling the extension of a connection from said trunk to the designated one of said special service positions, said marker comprising rst means responsive to the registration in said sender of the two preselected digits prexing a special service code, second means operable in response to the value of the rst of said special service code digitsffor transmitting an indication thereof, third means selectively operable in response to the registration in said sender of a second special service code digit greater or less than a preselected Value and in response to said first means for translating the indication transmitted by said second means and for transmitting an indication thereof, fourth means for translating an indication of the value of the second of said special service code digits and an indication of the value of the third of said special service code digits and for transmitting an indication thereof, and means for translating the indications transmitted by said third means and said fourth meansland for transmitting an indication for actuating means to control the extension of said connection.

JAMES B. NEWsoM. i

REFERENCES CITED UNITED STATES PATENTS Y Name Date Korn Nov. 18, 1941 Number 

